2  Lab Exercise 8

In this exercise, you’ll be using the terra and tidyterra packages to transform a raster dataset, sample it, and then visualize it. The data you’ll be using is satellite imagery from an area near Lake Turkana in Kenya (eastTurkana.tif). These data contain four layers: three values that are in the visual spectrum (red, green, and blue), and then one in near-infrared (nir).

• These sensor reflectance values, called “digital numbers”, are highly exaggerated. To convert them to reasonable reflectance values, we need to divide them by 10000.

• Calculate the Normalized Difference Vegetation Index: a measure of vegetation greenness that is used as an indicator of vegetation cover. The equation for this is NDVI = (NIR — RED)/(NIR + RED)

NDVI values below 1 are indicative of cloud cover or water, while values below 0.1 are usually indicative bare earth. When plotting, visualize these using a palette that emphasizes a different values that are greater or less than 0.1.

Include your code in a Quarto document with appropriate headings and descriptive text. Grading criteria are available on Canvas